MUX 4 Click as its foundation uses the 74HC4851, a precise 8-channel analog multiplexer/demultiplexer from Nexperia USA Inc. The 74HC4851 comes with eight independent input/output channels labeled from CH1 to CH8 that accept analog and digital signals of any voltage up to 5V. Compared to its predecessors, the 74HC4851 is better to use for the simple reason that it has a higher tolerance to a disturbance on channels that are not connected. Thanks to its characteristic of being both a multiplexer and a demultiplexer, the signals can travel in both directions.

The injection-current effect control, which is integrated inside the 74HC4851, allows signals at disabled analog input channels to exceed the supply voltage without affecting the signal of the enabled analog channel. This feature eliminates the need for external diode/resistor networks typically used to keep the analog channel signals within the supply-voltage range.

MUX 4 Click communicates with MCU using several GPIO pins. With EN pin, routed to the CS pin on the mikroBUS™ socket, is set to its low logic state, one of the eight switches is selected by three pins labeled as S0, S1, and S2 routed to the RST, PWM, and INT pins on the mikroBUS™ socket. With EN pin is set to its high logic state, all switches are in the high-impedance OFF-state, independent of S0 to S2 pins.

In addition to its eight independent input/output pins, the 74HC4851 also has a common input/output pin where it is possible to select the signal input to a given pin, more precisely, whether the signal will be brought externally from the terminal labeled as I/O or from mikroBUS™ socket AN pin. Selection can be performed by onboard SMD jumper labeled as I/O SEL to an appropriate position marked as AN and EXT. The MUX 4 Click comes equipped with one nine-position spring terminal for all input/output signals, making all wire connections reliable and straightforward.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it allows both 3.3V and 5V capable MCUs to use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development